The spectrum of COVID-19 infection includes acute respiratory distress syndrome (ARDS) and macrophage activation syndrome (MAS), although the histological basis for these disorders has not been thoroughly explored. Post-mortem pulmonary and bone marrow biopsies were performed in 33 patients. Samples were studied with a combination of morphological and immunohistochemical techniques. Bone marrow studies were also performed in three living patients. Bone marrow post-mortem studies showed striking lesions of histiocytic hyperplasia with hemophagocytosis (HHH) in most (16/17) cases. This was also observed in three alive patients, where it mimicked the changes observed in hemophagocytic histiocytosis. Pulmonary changes included a combination of diffuse alveolar damage with fibrinous microthrombi predominantly involving small vessels, in particular the alveolar capillary. These findings were associated with the analytical and clinical symptoms, which helps us understand the respiratory insufficiency and reveal the histological substrate for the macrophage activation syndrome-like exhibited by these patients. Our results confirm that COVID-19 infection triggers a systemic immune-inflammatory disease and allow specific therapies to be proposed.

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Oral lesions in primary Sjögren's syndrome compared to a control group

Background Rituximab may benefit patients with connective tissue diseases (CTD). Objectives We present here short-term safety and clinical outcomes of rituximab in CTD-associated interstitial lung disease (ILD) in a real-life clinical setting. Methods All patients with CTD-associated ILD treated with rituximab in our ILD clinic were included. Efficacy was assessed by pulmonary function tests and high-resolution computed tomography (HRCT). Results are expressed as median (limits). ILD exacerbations and safety were assessed. Results A total of 14 patients with CTD-associated ILD (29% rheumatoid arthritis, 21% primary Sjögren syndrome, 21% unclassifiable CTD, 14% systemic sclerosis and 14% inflammatory myopathy) received a dose of 4000 (2000 – 6000) mg Rituximab over an observation period of 161 patient-year. The distribution of morphologic ILD patterns were: 57% usual interstitial pneumonia (UIP), 21% unclassifiable ILD, 7% nonspecific interstitial pneumonia (NSIP), 7% cryptogenic organizing pneumonia (COP) and 7% lymphoid interstitial pneumonia (LIP). At baseline, IgG levels and leukocyte subset counts were within normal range, with reduced numbers of unswitched memory B cells. Incidence infection rate during RTX therapy was 4.35/100 patient-month with only one case being severe. There was 1 death, due to neutropenia with a disseminated fungal infection. Longitudinal pulmonary function data available in 12 patients showed an overall improvement in FVC (85%±19 versus 73%±18) and DLCO (58%±18 versus 45%±19). Radiographic progression could be evaluated in 6 patients, with five showing lack of progression and one improvement. ILD incidence relapse rate during rituximab therapy was 0.745/100 patient-month compared to 5.56/100 patient-month during the pre-treatment period. Conclusions Our preliminary data indicate that rituximab is safe in the study population. Our patients had a notoriously low exacerbation rate. Although optimal outcome measures in the short term are difficult to establish, we could confirm disease stabilization in most patients. Disclosure of Interest None Declared